1. Field of the Invention
This invention relates to wireless networking and more particularly relates to rapid wireless network association.
2. Description of the Related Art
Wireless networking technology is rapidly overtaking standard hardwired networks. For example, five to ten years ago a Local Area Network (LAN) was typically hardwired. Today, Wireless Local Area Networks (WLANs), wireless “hotspots”, and the like are becoming common place. WLAN technology is being implemented in home, office, school, and other environments. WLAN technology is popular because it is generally less expensive, more portable, and more easily installed and maintained than traditional wired networking infrastructure.
Wireless networks are typically configured as a peer to peer network, a client to access point network, or a multiple client/multiple access point network. Generally a Wireless Access Point (WAP) is a wireless transceiver with its associated control structure that interfaces a wired network infrastructure on one end and a wireless client on another end. WAPs are commonly referred to as Wireless routers, although a WAP does not necessarily need to be a packet routing device.
For example, a client may include a laptop with a wireless network card plugged into its Personal Computer Memory Card International Association (PCMCIA) or internal Mini-PCI or Mini-PCI Express interface slot. A WAP may be a packet routing device connected to a T-1 wired landline. The WAP generally includes one or more antennas which transmit a Radio Frequency (RF) signal to the client. The client typically responds with another RF signal, and a wireless network link can be established.
Various communication standards have been developed to regulate transmission power levels, frequencies, security, and interference. The generally accepted standards are defined by the Institute of Electrical and Electronics Engineers (IEEE) standards 802.11a, 802.11b, and 802.11g. Additional standards may be used such as the new IEEE 802.11n standard and others. Wireless networking infrastructure typically operates in accordance with one or more of these standards. For example some wireless cards operate on both the IEEE 802.11a and 802.11b standards. In this example, the wireless card is capable of communicating at either the 5 GHz band as specified by the 802.11a standard or at 2.4 GHz as specified by the 802.11b and 802.11g standards.
Typically each standard specifies a range of frequencies for operation broken up into multiple channels. For example, IEEE 802.11b specifies operation between 2.402 GHz and 2.472 GHz. This frequency range of operation is typically referred to as the frequency band of operation. For 802.11b and 802.11g, the frequency band is typically broken into up to fourteen overlapping 20 MHz channels. Under 802.11a, 20 MHz channels are also defined but they are spread over the 5 GHz UNII band, which divides into up to 27 different channels. In a typical system, a WAP will put out a signal referred to as a beacon on a predefined frequency channel. A client may scan channel by channel to detect the transmitted beacon. If a client detects a beacon from a WAP, the client will attempt to associate with the WAP. However, as the number of acceptable standards grows, and as wireless components become capable of handling data transmissions in accordance with multiple standards, the time required to scan more and more channels is greatly increasing initial network association times.
In certain configurations, heterogeneous networks are formed when the RF radiation patterns of multiple WAPs overlap in the proximity of a client. For example, FIG. 1 is a schematic block diagram illustrating a typical WLAN network configuration of the prior art. The WLAN typically includes one or more WAPs 102. For illustrative purposes, assume that WAP 102A operates under the IEEE 802.11a standard, WAP 102B operates under the 802.11b standard, and WAP 102C operates under the 802.11g standard. The system also includes a client 104. In this example the client is a laptop computer coupled to a PCMCIA wireless networking card 106. Each WAP 102A-C and the wireless networking card 106 includes an attached RF antenna 108. In this example, the RF signals 110A-C representing the beacon transmitted by the antennas 108 on each of the WAPs 102A-C overlap in the proximity of the client 104. The frequency and power level of the signals 110A-C are determined in accordance with the associated networking standard IEEE 802.11a, b, or g.
If the wireless card 106 is capable of handling communications on any one of IEEE 802.11a, b, or g, then the wireless card may need to scan up to 50 separate channels to find an active network. Typically, the operation of passive channel scanning includes starting on the lowest channel of a given frequency band, scanning the channel for energy related to data communications or a WAP beacon, and then moving to the next channel if no energy is found. If a client capable of multiband communication cannot find an active channel in one band, it begins the scanning process on the first channel of the next frequency band. Each channel scan requires over two seconds; therefore the time to associate with a network may take minutes not seconds, which is an unacceptably long time by typical networking standards. By way of contrast, in wired networks IEEE standards require network association within 3 seconds total.
From the foregoing discussion, it should be apparent that a need exists for an apparatus, system, and method that rapidly associate with a wireless network. Beneficially, such an apparatus, system, and method would reduce the required scanning time associated with locating an active communication channel and associating with the active network.